Self-sharpening knife



Dec. 13, 1932. v v NK ET AL v 1,890,506

SELF SHARPENING KNIFE Filed May 14, 1932 I ATTORNEY.

v I /////////I;//////////// =1%/0 W\ XJ Patented Dec. 13, 1932 UNITED STATES PATENT OFFICE.

EARL FRANK AND JOHN D. KIBBEY, OF INTERNATIONAL FALLS, MINNESOTA SELF-SHABYENING KNIFE Application filed May 14, 1932. Serial No. 611,264.

This invention relates to knives and more especially to kitchen knives.

The prime object of the invention is to provide in a relatively simple, compact and etficient'form, a knife assembly including a blade slidably mounted within the handle and a sharpening means incorporated within or upon the handle in such position that the edge of the blade will be caused to travel I Y along or over such sharpening means as the blade is reciprocated in and out of the handle, whereby the edge of the blade will be sharpened.

Another object is to provide a self-sharpening knife, including a hollow handle and a blade recprocatingly mounted therein and supported at the end of a blade rod longitudinally and slidably extended through the handle in such a way that the blade may be thrust longitudinally out at one end of the handle for use, or may be reciprocated in and out of the handle for the purpose of sharpening the edge of'the blade, there being a sharpening element mounted upon the handle for this purpose.

Another object is to provide a knife of the kind referred to, the same comprising a hollow handle and a blade slidably mounted thereYn through one end, there being a sharpening element mounted at the end of the handle through which the blade passes, whereby the edge of the blade may be sharpened as it moves or is moved in and out of the handle, there being a blade rod extended from the rear end of the the rear end of the handle as means for reciprocating the blade in and out of the handle over the sa d sharpening element, there being 46 provided also means for normally projecting the blade outwardly of the handle for use and means for releasably locking the blade in such out-thrust position.

WVith these and such o;her and further objects and purposes n view as may be developed in the following specification, atten tion is now directed to the accompanying drawing as illustrating certain preferred'cmbodiments of the invention and certain preferred structural features thereof, and wherein blade out through Figure 1 is a side elevation of a knife constructed in accordance with this invention, the blade being shown extended as for use.f

Figure 2 is a View similar to that of Figure 1', showing half of the two-part hollow handle removed to reveal the interior structure andarrangement of the parts, the leaf spring ut lized as the holder for the sharpening rolls being shown in longitudinal section, as also the ferrule at the end of the handle and the blade rod within the handle, the rear end of the latter, however, being represented in full. Figure 3 is a view similar to that of Figure 2, the blade, however, being shown as partially drawn back within the handle as in the act of sharpening the edge thereof, and the rear end of the blade rod being broken off.

Figure 4 is a transverse section on the line 4-4 of Figure 3.

Figure 5 is a longitudinal transverse section through the assembly of Figure 1, the blade, however, being shown in full, and also the blade rod, except that the forward end thereof is shown 1n section and partly broken away for illustrating the method of anchoring that end of the coil spring here used for impelling the blade outwardly from the handle.

Figure 6 is an elevation showing a modified method 'of mounting the sharpening element, the forward end of the frontal side of the handle being broken away.

Figure 7 is a fragmental detail of the connected portions of the blade and blade rod. Figure 8 is an enlarged transverse sectional detail of the rear end of the assembly shown in Figure 1, the forward portion of the assembly being broken away.

The invention comprises an elongated hollow handle 1 shown here as made up of two equal halves 2 adapted to be secured together by means of a ferrule 3 at the forward end and by set screws 4 at the rear end in a conventional manner. The ferrule 8 is slotted as shown at 5 sothat the knife blade 6 may be slidably passed therethrough. This blade is preferably formed integrally with a'hollow or tubular blade rod 7 which is passed slidably out through an aperture 8 formed through the rear inturned ends of the two connected handle halves or sections. The blade and blade rod may be very conveniently stamped integrally from sheet metal, and then the blade rod formed by rolling up the rear end of the strip upon its longitudinal axis into the form of a parted tube shown in the drawing. Thus this blade rod will be formed with an'opcning 9 leading thereinto at the point of juncture of the rod with the blade 6. This structure will afford a useful purpose as will be later pointed out. The rear end of the blade rod 7 is split longitudinally as shown at 10 and sprung laterally asunder, and the extremities of the split ends are rounded in as shown at 11, so as to conj ointly form a sort of knob for the accommo- (lat-ion of the user. Laterally positioned notches 12 are formed in the split ends 11 adaptedtoengage the interned margins 13 of the ends of the handle sections 2. whereby the knife blade is automatically locked in its out-thrust position, when the rod 7 is pushed fully inward. As shown in Figures 1, 2, 3 and 7. the blade 6 at its point of juncture with the rod 7 is beveled down to the rod as shown at 14, and the importance of this feature will later appear. A sharpening element 15 is provided and mounted at the junc ture of the blade 6 and rod 7 at the edge side of the blade in such a way that as the rod 7 is pulled back through the handle and then projected forward again. the edge of the blade will be drawn over this sharpening element, whereby the blade is sharpened.

As shown in Figures 1. 2. 3 and 4. the sharpening element 15'eonsists of a pair of tempered steel rolls rotatively mounted side by side upon small pins 16 having their ends anchored in the spaced ends of a U-shaped bracketor holder 17. This bracket is mounted upon the forward free end of a leaf spring 18, the opposite. end of the spring being fastened at 19 tothe under side of the handle immediately at the inner end of an elongated slot 20 formed through the under side of the forward end of the handle. Thus the spring 18 will normally cover the said slot 20 and lie close to the handle and the sharpening element 15 will lie normally within the handle in'nnediately back of the taper or bevel 14 marking the juncture of the blade 6 and blade rod '7. It will now be apparent that by merely pressing together the two halves 11 of the split end of the rod 7, the notched portions will he released from engagement with the margins 13 of the handle. and the. rod may then be drawn backward out through the rear end of the handle. In turn the attached blade 6 will, of course, be drawn back within the handle. and the sharpening elenwnt 15 will climb the bevel 14 and ride upon the cutting edge 21 of the blade, as clearly shown in Figure 3. thus sharpening the blade as same is pulled back into the handle. In this operation the free end of the spring 18 to lock the blade 6 in its out-thrust position I ready for use. If desired, a long coil sprin 22 may be seated within the tubular rod 7 through the opening 9, the rear end ofthe spring being fastened at 23 to the tube and the forward end at 24 to the inner face of the handle. This spring being drawn taut, will serve to automatically project the blade outward after each pull upon the rod 7. and will help hold the blade out in its normal working position. This spring. however. is not absolutely essential to the perfect functioning of the knife and the sharpening element.

As shown in Figure (3, the spring 18 is omitted. nor is the handle slotted as at 20. as shown in the preceding figures of the,

drawing. The holder 17 is freely mounted I within a housing 25 offset from the handle and opening thereinto. A small coil spring 26 is interposed between the end of the housing and the holder. whereby the latter is normally pressed outward and against the edge of the blade 6 as the same is reciprocated in the manner described for the preceding form of assembly. If desired. a set screw 27 may be passed through the back of the ferrule 3 and into a small notch 28 in the back of the blade 6. as means for releasably locking the blade against loose motion.

It is thought from the foregoing description that the use and operation of the device will be fully understood.

The principles here embodied and described in reference to a kitchen knife might easily be applied to other kinds of knives. So also the sharpening element or cutters might be used for other purposes, and while we have herein described and illustrated certain forms of our invention. including certain structural features, it is understood that we may vary from the same in details, not departing from the spirit of the invention, as defined in the appended claims.

\Ve claim: I

1. In a device of the kind described, an elongated. hollow handle having an elon-. gated slot formed through one side near one end. a leaf spring mounted over the slot and having one end fastened to the handle at the inner end of the slot. the forward end of the spring being free. a sharpening element nmunted at the inner side of the free end of the spring. a knife blade and connected blade rod reciprocatingly mounted through the handle, the blade being at the same end with the sharpening element and the edge ot the blade being turned towards said element, the said blade being beveled at its juncture with the said blade rod so as to enable the sharpening element to clamp and ridoupon the edge of the blade as the same is drawn backward.

In a device of the kind described, an elongated, hollow handle having an elongated slot formed through one side near one end, a leaf spring mounted over the slot and having one end fastened to the handle at the inner end of the slot, the forward end of the spring being free. a sharpening element mounted at the inner side ot' the free end of the spring,

a knife blade and connected blade rod re-.

ciprocatingly mounted through the handle. the blade being at the same end with the sharpening element and the edge of the blade being turned towards said element, the said blade being beveled at its juncture with the said blade rod so as to enable the shar 'iening element to clamp and ride upon thetedgeot the blade as the same is drawn backward, the. rear end of the blade rod being aplit and the sundered parts notched to lockingly engage the inturned margins of the end of the handle.

3. In a device of the kind described, an elongated, hollow handle having an elongated slot formed through one side near one end,

a leaf spring mounted over the slot and hav- 1 ing one end fastened to the handle at the inner end of the slot. the forward end of the spring being free. a sharpening element mounted at the inner side of the free end oi the spring. a knife blade and connected blade rod reciprocatingly mounted through the handle. the blade being at the same end with the sharpening element and the edge of the blade being turned towards said element, the said blade being beveled at its juncture with the said blade rod so as to enable the sharpening elementto clamp and ride upon the edge of the blade as the same is drawn liiackward, the rear end of the blade rod being split and the sundered parts notched to lockingly e11- gagethc inturned margins of the end oi the handle. and means for automatically projecting the blade to its normal out-thrust position.

4. In a device. of the kind described, an elongated, hollow handle having a blade slotthrough one end, a blade rod aperture through the other end, and an elongated sharpener slot through one side immediately back of the blade slot, a connected blade and blade rod reciproeatingly mounted through the handle with the blade through the blade slot and the blade rod through the blade rod aperture, the edge of the blade being turned element mounted at the inner side of the free. end of the spring. the said blade being beveled at its juncture with the blade rod. whereby the sharpening element may clamp to the edge of the blade as the latter is drawn back into the handle.

5. In a device ot the kind described. an elongated. hollow handle having a blade slot through one end. a blade rod aperture through the other end. and an elongated sharpener slot through one side immediately back of the blade slot, a connected blade and blade rod reciprocatingly mounted through the handle with the blade through the blade slot and the blade rod'through the blade rod aperture, the edge of the blade being turned towards said elongated sharpener slot, a leaf spring mounted o'ver the sharpener slot. one end thereof being tastened to the handle at the inner end of the slot. and a slnirpening element mounted at the inner side of the free end ot the spring, the said blade being beveled at its juncture with the blade rod, whereby the sharpening element may clamp to the edge of the blade as the latter is drawn back into the handle, and a spring connecting the blade rod to the handle to normally project the blade out 'ardly.

(3. In a device of the kind described, an elongated, hollow handle having a blade slotv through one end, a blade rod aperture through the. other end, and an elongated sharpener slot through one side immediately back of the blade slot. a connected blade and blade rod reciproeatingly mounted through thehandle with the blade through the blade slot and the blade rodthrough the blade rod aperture, the edge of the blade being turned towards said elongated sharpener slot, a leaf spring mounted over the sharpener slot. one end thereof being fastened to the handle at the inner end of the slot, and a sharpening elementmounted at the inner side of the free end of the spring, the said blade being beveled at its juncture with the blade rod, whereby the sharpening element may clamp to the edge of the blade as the latter is drawn back into the. handle. a spring connecting the blade rod to the handle to normally project the blade outwardly, and means for releasably locking the blade and blade rod against longitudinal movement.

In testimony whereof, we afiix our s1gna= tures.

EARL L. FRANK. JOHN KIBBEY.

towards, said elongated sharpener slot. a leaf spring mounted over the sharpener slot. one

end thereof bein fastened to the handle at the inner end ot the slot, and a sharpening 

